textproduct: Quad Cities

KEY MESSAGES

- Areas of Dense fog this morning, another MCS rolling in from the west this morning with potential severe weather, and more storms tonight with flash flooding/flooding becoming more in the spotlight.

- The active weather pattern will bring a daily risk of showers and thunderstorms Friday and through the weekend. HOWEVER, there will be and many hours of dry weather each day.

SHORT TERM /THROUGH TONIGHT/

Issued at 315 AM CDT Thu Aug 13 2026

Light sfc winds and a juiced boundary layer making for some fog problems early this morning until more clouds and precip arrive from the west. Fog Advisory issued. Now eyes turn to the convectively enhanced short wave out acrs NE and associated convective complex of storms out that way. Propagation vectors and optimal thermal tracks bring this feature acrs the DVN CWA mid to late morning. Still some MLCAPE of 1500-2500 J/kg to work with but shear not as strong as the last two mornings and quite an EML to overcome for more sfc rooted behavior. But a later morning arrival and wave associated shear may help and still see a damaging wind threat of 60- 70 MPH posssible as well as a few embedded tornadoes. A 2 inch PWAT feed will also fuel heavy rain at heavy rainfall rates thus the flooding risk is going up. Have issued a Flood Watch for the south half of the DVN CWA starting this morning to cover the brunt of the passing MCS banking on the more intense part of it moving along and south of I-80. But then having the watch go tonight into Friday midday as well for additional bouts of heavy rain and thunderstorms with a 2+ inch PWAT feed and airmass in place.

For most of the north half of the DVN CWA, started the flood watch tonight and continue it through the same end time of 18z Friday. These areas may get clipped by not quite as heavy rain this morning/midday, have a partial break for the rest of the afternoon and early evening before the convergent nocturnal LLJ kicks in and ignites more thunderstorms along thermal gradients or lingering boundaries. Feed and shear profiles supports repeated storm development and back-building along linear segments tonight, and with a 2 inch PWAT airmass this spells swaths of flash flooding trouble. For now reluctantly left out the Hwy 20 corridor from the flood watch with still ongoing uncertainty where the main line or lines of storms lay out, but after assessment later today there may be the eventual need to add these counties to the watch as well. The north may switch positions with the south as several of the latest CAMs have little overnight activity south of I-80.

Although still muggier than a dog's mouth today, with east winds and convective debris will limit the need for any heat headlines at this point.

LONG TERM /FRIDAY THROUGH WEDNESDAY/

Issued at 315 AM CDT Thu Aug 13 2026

Friday...There may be some lingering flooding problems in the morning, but convective coverage should be diurnally waning into the midday. Boundary placement should make for high temp variance from the upper 70s north, to the upper 80s in the far south. Timing the next ridge-riding short wave may bring yet another MCS in from the west by late afternoon and into Friday evening. This would bring more damaging wind threats as well as more heavy rain to a potentially water sensitive CWA and there may be a need of another flood watch. Area creeks and rivers could be really on the rise at that time as well, will have to keep the hydrological aspects more in mind as well as the severe risks.

Saturday through Wednesday...Latest ensemble and upper jet trends suggest the upper ridge and heat dome to get pressed eastward temporarily maintaining the ring of fire for the weekend with the local area dangerously near the periphery through at least Sunday. Storm chances will continue as well as a hot humid Saturday in store, but then some signs early next week of upper ridge retro-grade allowing for more of a northwest flow push down the upper MS RVR Valley. A resultant drier and cooler Monday would be much welcome by then.

AVIATION /12Z TAFS THROUGH 12Z FRIDAY/

Issued at 605 AM CDT Thu Aug 13 2026

A challenging TAF cycle with areas of fog and low stratus trending into an incoming large severe MCS from the west by mid morning, then more storms along some axis from west-to-east tonight. The MCS will have the associated hazards and potential high wind gusts. After the MCS passage, some of the afternoon there may be a precip lull window or a lingering linear line low coverage west-to-east of showers/storms somewhere. Later tonight with nocturnal LLJ kicking in along LLVL remnant boundaries, there could be bands of persistent thunderstorms and be a big impact if they camp out over a TAF site or two with heavy rain. Away from the variable gusts of the thunderstorms, with the main sfc boundary shunted to the south, the ambient winds will be generally from the east or have some easterly component for much of the TAF period.

DVN WATCHES/WARNINGS/ADVISORIES

IA...Flood Watch from this evening through Friday afternoon for IAZ051>054-063>068. Dense Fog Advisory until 9 AM CDT this morning for IAZ053-054- 064>068-076>078-087>089-098-099. Flood Watch through Friday afternoon for IAZ076>078-087>089- 098-099. IL...Flood Watch from this evening through Friday afternoon for ILZ007-009-015>018. Dense Fog Advisory until 9 AM CDT this morning for ILZ001-002- 007-009-015>018-024>026-034-035. Flood Watch through Friday afternoon for ILZ024>026-034-035. MO...Dense Fog Advisory until 9 AM CDT this morning for MOZ009-010. Flood Watch through Friday afternoon for MOZ009-010.